在where子句中使用计算列

Question

我正在尝试在where子句中使用计算列.

我已尝试从CROSS APPLY到子查询选择的所有内容,但它并没有给我任何接近我需要的东西.

我的查询到目前为止:

SELECT p.Code, c.AccountNumber, Sales = (SUM(p.UnitPrice) * SUM(od.QtyShipped)) FROM [dbo].Customer c 
    LEFT JOIN [dbo].OrderHeader oh ON oh.CustomerId = c.Id 
    LEFT JOIN [dbo].OrderDetail od ON od.OrderHeaderId = oh.Id
    LEFT JOIN [dbo].Product p ON p.Id = od.ProductId
WHERE Sales > 100
GROUP BY p.Code, c.AccountNumber, Sales

这不起作用,因为'Sales'是无效列

Answer 1

您需要将内部查询包装在派生表或CTE中,以便能够在WHERE子句中使用派生列(另外,注释SUM()在乘法后仅指定一次):

SELECT x.Code, x.AccountNumber, x.Sales
FROM
(
  SELECT p.Code, c.AccountNumber, SUM(p.UnitPrice *od.QtyShipped) AS Sales 
  FROM [dbo].Customer c 
      LEFT JOIN [dbo].OrderHeader oh ON oh.CustomerId = c.Id 
      LEFT JOIN [dbo].OrderDetail od ON od.OrderHeaderId = oh.Id
      LEFT JOIN [dbo].Product p ON p.Id = od.ProductId
  GROUP BY p.Code, c.AccountNumber
) AS x
WHERE x.Sales > 100;

Answer 2

您可以为此使用公用表表达式

;WITH CTE AS
    (
    SELECT p.Code, c.AccountNumber, Sales = (SUM(p.UnitPrice) * SUM(od.QtyShipped)) FROM [dbo].Customer c 
        LEFT JOIN [dbo].OrderHeader oh ON oh.CustomerId = c.Id 
        LEFT JOIN [dbo].OrderDetail od ON od.OrderHeaderId = oh.Id
        LEFT JOIN [dbo].Product p ON p.Id = od.ProductId
    
    GROUP BY p.Code, c.AccountNumber, Sale
    
    )
    
SELECT *
FROM CTE WHERE CTE.Sales>100